Motor For Driving Lens

ABSTRACT

A motor for driving a lens is disclosed, wherein a yoke comprises a rotation prevention unit configured to prevent the bobbin from rotating.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/202,037, filed Aug. 17, 2011, which is the U.S. national stageapplication of International Patent Application No. PCT/KR2010/000985,filed Feb. 17, 2010, which claims priority to Korean Application Nos.10-2009-0012860, filed Feb. 17, 2009, and 10-2009-0024430, filed Mar.23, 2009, the disclosures of each of which are incorporated herein byreference in their entirety.

TECHNICAL FIELD

The present invention relates to a motor for driving a lens.

BACKGROUND ART

Concomitant with a recent trend toward multifunctional digital devices,a digital device embedded with a camera and an MP3 player has beendeveloped and used. Further, a camera lens embedded in the digitaldevice is automatically moved and adjusted by a motor for driving a lens(hereinafter referred to as “lens-driving motor”).

The lens-driving motor has a base and a housing, each coupled together.The housing is disposed therein with a liftable carrier supported by aspring, and the carrier is disposed at an inner surface thereof with alens.

The lens is screwed to the carrier. That is, the inner surface of thecarrier and a periphery of the lens are correspondingly formed with ascrew line, whereby the lens is inserted into the carrier and rotatedthereinside to allow the lens to be coupled to the carrier.

In a case the lens is inserted into the carrier and rotated thereinside,the carrier is also rotated by torque. In a case the carrier is rotatedfor more than a predetermined angle, the spring experiences the plasticdeformation, rendering the carrier to function in an unsatisfactory way.

However, there is a disadvantage in the conventional lens-driving motorin that there is no means for preventing the carrier from rotating formore than a predetermined angle, resulting in degraded reliability dueto the plastic deformation of the spring.

Meanwhile, an attempt is required to slim and miniaturize thelens-driving motor by integrally forming the carrier and the spring toshorten the assembly process, and to constantly maintain an initiallycoupled status between the carrier and the spring lest the carrier andthe spring should be easily separated or deformed.

TECHNICAL PROBLEM

The present invention is disclosed to obviate the abovementionedproblems, and it is an object of the present invention to provide alens-driving motor configured to prevent a spring from experiencing theplastic deformation caused by an assembly torque during assembly betweena lens and a carrier. Another object is to provide a lens-driving motorconfigured to simplify and improve an assembled structure between thecarrier and the spring and to constantly maintain an initial status lesta coupled structure between the carrier and the spring should be easilydestructed.

TECHNICAL SOLUTION

In one general aspect of the present invention, there is provided avoice coil motor, comprising: a mover including a bobbin including alower bobbin portion having a lens secured therein and an upper bobbinportion protruded from an upper surface of the lower bobbin portion in adirection parallel to an optical axis of the lens, and a coil secured toa periphery of the lower bobbin portion; at least one magnet facing thecoil; a yoke fixing the at least one magnet and comprising a rotationprevention unit configured to prevent the bobbin from rotating; and anelastic member supporting the bobbin, wherein the rotation preventionunit comprises: a lateral portion extending laterally from the yoke; anda downward portion extending downwardly from the lateral portion towardthe upper surface of the lower bobbin portion.

In another general aspect of the present invention, there is provided anoptical device comprising a voice coil motor and a lens and a sensor,wherein the voice coil motor, comprising: a mover including a bobbinincluding a lower bobbin portion having a lens secured therein, an upperbobbin portion cylindrically protruded from an upper surface of thelower bobbin portion, at least one rotation prevention groove formed inthe upper bobbin portion and exposing an upper surface of the firstbobbin within the at least one rotation prevention groove, and a coilsecured to a periphery of the lower bobbin portion; at least one magnetfacing the coil; a yoke fixing the at least one magnet and comprising arotation prevention unit extended to the rotation prevention groove toface the upper bobbin portion; and an elastic member supporting thebobbin, wherein the rotation prevention unit comprises: a lateralportion extending laterally from the yoke; and a downward portionextending downwardly into the rotation prevention groove and toward theupper surface of the lower bobbin portion.

ADVANTAGEOUS EFFECTS

The lens-driving motor according to the present invention isadvantageous in that one side of an outer surface of a carrier issupportively inserted into a yoke fixed at a housing to prevent thecarrier from rotating at a predetermined angle or more, whereby a springsupporting the carrier is not rotated at a predetermined angle or moreeither, and the spring is deformed only within a scope of elastic limitto allow the spring to properly function at all times to an enhancedreliability of the product.

The lens-driving motor according to the present invention is furtheradvantageous in that through holes through which the carrier passes areformed at an inner surface of the spring buried in a periphery of thecarrier, whereby the spring is prevented from being disengaged from thecarrier to an enhanced reliability of the product.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a lens-driving motor according to anexemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view along line “A-A” of FIG. 1.

FIGS. 3 and 4 are enlarged views of a “P” part and a “Q” part of FIG. 2.

FIG. 5 is an exploded perspective view of an essential part of FIG. 1.

FIG. 6 is a cross-sectional view of a lens-driving motor according to anexemplary embodiment of the present invention.

FIG. 7 is a plan of a spring illustrated in FIG. 6.

FIGS. 8 and 9 are enlarged views of a “A” part and a “B” part of FIG. 6.

FIGS. 10 and 11 are enlarged views of an essential part in alens-driving motor according to another exemplary embodiment of thepresent invention.

DETAILED DESCRIPTION

A lens-driving motor according to exemplary embodiments of the presentinvention will be described in detail with reference to the accompanyingdrawings.

FIG. 1 is a perspective view of a lens-driving motor according to anexemplary embodiment of the present invention, FIG. 2 is across-sectional view along line “A-A” of FIG. 1, and FIGS. 3 and 4 areenlarged views of a “P” part and a “Q” part of FIG. 2.

As illustrated, a lens-driving motor according to the present inventionincludes a base (110) and a housing (120) each coupled together to forman inner space therebetween. In designating a direction and a surface ofconstituent parts including the base (110), a direction and a surfacefacing an upper vertical side of the base (110) are respectively called“an upper side” and “an upper surface”, while a direction and a surfacefacing a bottom vertical side of the base are respectively called “abottom side” and “a bottom surface”.

The housing (120) is coupled at a bottom surface to the base (110). Anedge of the base (110) is formed with a stair (111) into which a bottomsurface of the housing is inserted, whereby foreign objects areprevented from entering a coupled part between the base (110) and thehousing (120). An upper surface of the base (110) and the housing (120)is formed with a through hole (113) and an inlet/outlet hole (123) eachfacing the other.

A yoke (130) is formed at an inner surface of the housing (120).Meanwhile, it should be apparent that the housing (120) may be coupledwith the yoke (130), or the housing itself may be a yoke. The yoke (130)may include a square frame-shaped outer wall (131), an ring-shaped innerwall (133) formed inside the outer wall (131), and a connection plate(135) connected to an upper end surface of the outer wall (131) and toan upper end surface of the inner wall (133) to integrally connect theouter wall (131) and the inner wall (133).

The outer wall (131) of the yoke (130) and the connection plate (135)are wrapped by the housing (120) to form an integrated shape. At thistime, an accommodation groove (125) is formed at an inner surface of thehousing (120) for the outer wall (131) of the yoke (130) to be insertedand accommodated therein, whereby the yoke (130) is integrally andsecurely formed with the housing (120).

An inner surface of an edge side of the outer wall (131) on the yoke(130) is disposed with a magnet (140), and an inner side of the innerwall (133) on the yoke (130) is liftably mounted with a carrier (150) toallow entering an inlet/outlet hole (123). A lens (200) is mounted at aninner surface of a carrier (150) and a coil (160) is wound on aperiphery of the carrier (150).

The coil (160) is oppositely formed from the magnet (140), and in a casea current flows in the coil (160), the coil (160) is lifted by anelectromagnetic force formed between the coil (160) and the magnet(140), which in turn raises the carrier (150) to lift the lens (200).The housing (120) is integrally formed with a ring-shaped resilientspacer for compensating a dimensional tolerance of parts and an assemblytolerance generated in the course of assembling the parts. The spacerincludes first and second spacers (171, 175) integrally and respectivelyformed at a bottom end surface and an upper end surface of the housing(120).

The housing is formed by injection molding, and the yoke (130) and thespacer are integrally formed during injection molding of the housing(120).

The carrier (150) lifted by the electromagnetic force is lowered by aspring including first and second springs (181, 185) to return to itsoriginal status.

To be more specific, an inner surface of the first spring (181) isintegrally formed with an outer surface of bottom side of the carrier(150), and an outer surface of the first spring (181) is inserted intothe base (110) and the first spacer (171) to be supported thereat. Aninner surface of the second spring (185) is coupled to an upper outersurface of the carrier (150), and an outer surface of the second spring(185) is inserted into a cover (190) coupled to an upper surface of thehousing (120) and the second spacer (175) to be supported thereat.

In a case a current flows in the coil (160) to lift the carrier (150),the first and second springs (181, 185) are elastically deformed, and ina case the current is stopped from the coil (160), the carrier (150)returns to an initial status by the elasticity of the first and secondsprings (181, 185).

Coupling holes (181 a, 185 a) and coupling protrusions (171 a, 175 a)are formed, each facing the other and the protrusions being insertedinto the coupling holes, at an outer surface of the first and secondsprings (181, 185) and the first and second spacers (171, 175). Thecover (190) is mounted on an upper surface of the housing (120) to coverthe second spacer (175) and to prevent foreign objects from entering thecoupled part between the base and the housing.

Screw threads are formed on an inner surface of the carrier (150) and anouter surface of the lens (200), each corresponding to the other, wherethe lens (200) is screwed to the carrier (150). That is, the lens (200)is inserted into and rotated in the carrier (150) to couple the lens(200) with the carrier (150), whereby the carrier (150) can be rotatedby torque. In a case the carrier (150) is rotated at a predeterminedangle or more, the first and second springs (181, 185) experience theplastic deformation to create a problem of not performing a properfunction.

The lens-driving motor according to the present invention prevents thecarrier (150) from rotating at a predetermined angle or more bysupporting the carrier (150) to the yoke (130), the operation of whichwill be described with reference to FIGS. 2 and 5. FIG. 5 is an explodedperspective view of an essential part of FIG. 1.

As shown in the figures, the carrier (150) is protrusively formed at anouter surface with a plurality of hitching rails (152) in parallel witha motional direction of the carrier (150), and an opening groove (130 a)is formed at the yoke (130) fixed at the housing (120) or at an innersurface of the housing (120), where the hitching rails (152) areinsertedly hitched by the opening groove (130 a), and the opening groove(130 a) and the hitching rails (152) are formed in parallel with themotional direction of the carrier (150).

In this case, even if the carrier is rotated by the torque generated inthe course of the lens (200) being coupled to the carrier (150), thehitching rails (152) are hitched at the housing or the yoke forming theopening groove (130 a) to prevent the carrier (150) from rotating at apredetermined angle or more.

The opening groove (130 a) is formed at a portion where the connectionplate (135) contacting the inner wall (133) and the inner wall (133) ofthe yoke (130) are joined.

Now, as an improvement to the aforementioned exemplary embodiment, anexemplary embodiment configured to reduce an assembly process byintegrally forming a carrier and a spring, and an exemplary embodimentconfigured to constantly maintain an initial status by preventing thecarrier and the spring from being easily separated or deformed will bedescribed.

FIG. 6 is a cross-sectional view of a lens-driving motor according to anexemplary embodiment of the present invention, FIG. 7 is a plan of aspring illustrated in FIG. 6, FIGS. 8 and 9 are enlarged views of a “A”part and a “B” part of FIG. 6 and FIGS. 10 and 11 are enlarged views ofan essential part in a lens-driving motor according to another exemplaryembodiment of the present invention.

Referring to FIGS. 6 to 11, a ring-shaped spring (180) is mounted atupper and bottom sides of the yoke (130). The carrier (150) lifted byoperations of the coil (160) and the magnet (140) returns to itsoriginal shape by the elasticity of the spring (180) if a current isstopped from flowing in the coil (160). The spring (180) includes aplurality of springs each having a different diameter that form aconcentricity. The spring (180) may include a first spring (181) mountedat an upper side of the first spacer (171) and a second spring (185)mounted at a bottom surface of the second spacer (175).

To be more specific, an inner surface of the first spring (181) isintegrally formed with an outer surface of upper side of the carrier(150), and an outer surface of the first spring (181) is inserted intothe housing (120) and the first spacer (171) to be supported thereat. Aninner surface of the second spring (185) is coupled to a bottom outersurface of the carrier (150), and an outer surface of the second spring(185) is inserted into the base (110) and the second spacer (175) to besupported thereat. The first and second springs (181, 185) areconfigured in the same shape and same construction but may differ indiameters thereof according to positions coupled to the carrier (150).

In order to simplify an assembled structure, the carrier (150) isinjection molded, and the spring (180) is integrally formed by an insertinjection molding method in which an inner side of the spring (180) isburied in an outer surface of the carrier (150) during injection of thecarrier (150).

Meanwhile, an area of an inner circumferential surface of the spring(180) that is buried by the outer surface of the carrier (150) tends togrow small due to slimness and miniaturization of the lens-drivingmotor, which may spawn the fear of disengaging the inner circumferentialsurface of the spring (180) from the carrier (150).

The lens-driving motor according to the present invention is configuredto prevent the spring (180) from disengaging from the carrier (150), theoperation of which will be described with reference to FIGS. 8 and 9.FIGS. 8 and 9 are enlarged views of a “A” part and a “B” part of FIG. 6.

Referring to FIGS. 8 and 9, an inner circumferential surface of thefirst and second springs (181, 185) that are buried in the outer surfaceof the carrier (150) are formed with a plurality of through holes (181a, 185 a), whereby an inner surface at the outer surface of the carrier(150) passes the through holes (181 a, 185 a) to be integrally formedwith the first and second springs (181, 185), such that the first andsecond springs (181, 185) are prevented from being disengaged from thecarrier (150).

The lens-driving motor according to the present invention is configuredin such a manner that a plurality of support holes (181 b, 185 b) areformed at an outer surface side of the first and second springs (181,185), and the support protrusions (123, 113) that are inserted into thesupport holes (181 b, 185 b) are formed at the housing (120) and thebase (110).

Then, the first and second springs (181, 185) are accurately coupled topreset portions of the housing (120) and the base (110) to prevent thefirst and second springs (181, 185) from rotating on the housing (120)and the base (110), whereby forces from the first and second springs(181, 185) are uniformly distributed on all areas of the carrier (150)to allow the carrier (150) to stably and accurately descend and ascend.

FIGS. 10 and 11 are enlarged views of an essential part in alens-driving motor according to another exemplary embodiment of thepresent invention, where only the difference from that of FIGS. 8 and 9will be described.

As illustrated, a plurality of support holes (281 b, 285 b) respectivelyformed at an outer surface side of first and second springs (281, 285)are respectively inserted by support protrusions (271 a, 275 a) formedat first and second spacers (271, 275). The first and second springs(281, 285) are accurately coupled to preset portions of a housing (220)and a base (210) to prevent the first and second springs (281, 285) fromrotating on the housing (220) and the base (210), whereby forces fromthe first and second springs (281, 285) are uniformly distributed on allareas of a carrier (250) to allow the carrier (250) to stably andaccurately descend and ascend.

While the present disclosure has been particularly shown and describedwith reference to exemplary embodiments thereof, the general inventiveconcept is not limited to the above-described embodiments. It will beunderstood by those of ordinary skill in the art that various changesand variations in form and details may be made therein without departingfrom the spirit and scope of the present invention as defined by thefollowing claims.

The lens-driving motor according to the present invention has anindustrial applicability in that one side of an outer surface of acarrier is supportively inserted into a yoke fixed at a housing toprevent the carrier from rotating at a predetermined angle or more,whereby a spring supporting the carrier is not rotated at apredetermined angle or more either, and the spring is deformed onlywithin a scope of elastic limit to allow the spring to properly functionat all times to an enhanced reliability of the product.

The lens-driving motor according to the present invention is furtheradvantageous in that through holes through which the carrier passes areformed at an inner surface of the spring buried in a periphery of thecarrier, whereby the spring is prevented from being disengaged from thecarrier to an enhanced reliability of the product.

1. A voice coil motor, comprising: a mover including a bobbin includinga lower bobbin portion having a lens secured therein and an upper bobbinportion protruded from an upper surface of the lower bobbin portion in adirection parallel to an optical axis of the lens, and a coil secured toa periphery of the lower bobbin portion; at least one magnet facing thecoil; a yoke fixing the at least one magnet and comprising a rotationprevention unit configured to prevent the bobbin from rotating; and anelastic member supporting the bobbin, wherein the rotation preventionunit comprises: a lateral portion extending laterally from the yoke; anda downward portion extending downwardly from the lateral portion towardthe upper surface of the lower bobbin portion.
 2. The voice coil motorof claim 1, wherein the lateral portion of the rotation prevention unitis extended laterally from the yoke, and the downward portion of therotation prevention unit is extended downwardly such that it is disposedin a rotation prevention groove formed in the upper bobbin portion. 3.The voice coil motor of claim 2, wherein the rotation prevention unit isconfigured such that a gap for ascending and descending the bobbin isformed between a distal end of the rotation prevention unit and theupper surface of the lower bobbin portion facing the rotation preventionunit.
 4. The voice coil motor of claim 2, wherein the yoke furthercomprises a plurality of rotation prevention units, the upper bobbinportion comprises a plurality of rotation prevention grooves, and thedownward portion of each rotation prevention unit is disposed in arotation prevention groove of the plurality of rotation preventiongrooves.
 5. The voice coil motor of claim 1, further comprising a casehaving an opening corresponding to the bobbin.
 6. The voice coil motorof claim 5, wherein the case comprises an upper plate having an openingfor exposing the bobbin.
 7. The voice coil motor of claim 1, wherein aninner lateral surface of the lower bobbin portion takes the shape of acylinder and an inner lateral surface of the upper bobbin portion takesthe shape of a cylinder having a substantially same curvature as that ofthe lower bobbin portion.
 8. The voice coil motor of claim 1, whereinthe upper bobbin portion comprises a plurality of rotation preventiongrooves, each spaced apart at equidistance.
 9. The voice coil motor ofclaim 1, wherein a thickness of the upper bobbin portion is thinner thanthat of the lower bobbin portion.
 10. The voice coil motor of claim 1,wherein the downward portion of the rotation prevention unit has a firstheight, and the upper bobbin portion has a second height taller than thefirst height.
 11. The voice coil motor of claim 1, wherein the yokefurther comprises: an upper plate having an opening for exposing thebobbin, and a lateral plate connected to the upper plate for fixing themagnet, wherein the lateral portion of the rotation prevention unit isextended from part of the upper plate of the yoke.
 12. The voice coilmotor of claim 1, wherein the yoke further comprises a plurality ofrotation prevention units, and each magnet is fixed in the yoke at aposition corresponding to that of a rotation prevention unit of theplurality of rotation prevention units.
 13. The voice coil motor ofclaim 12, wherein the rotation prevention unit is configured such that agap for ascending and descending the bobbin is formed between a distalend of the rotation prevention unit and the upper surface of the lowerbobbin portion facing the rotation prevention unit.
 14. The voice coilmotor of claim 1, wherein the downward portion of the rotationprevention unit comprises a curved plate having a substantially samecurvature as that of the lower bobbin portion.
 15. The voice coil motorof claim 1, wherein the upper bobbin portion comprises a boss protrudedfrom an upper surface thereof and coupled to the first elastic member.16. The voice coil motor of claim 1, wherein the downward portion of therotation prevention unit faces the upper bobbin portion.
 17. An opticaldevice comprising a voice coil motor and a lens and a sensor, whereinthe voice coil motor, comprising: a mover including a bobbin including alower bobbin portion having a lens secured therein, an upper bobbinportion cylindrically protruded from an upper surface of the lowerbobbin portion, at least one rotation prevention groove formed in theupper bobbin portion and exposing an upper surface of the first bobbinwithin the at least one rotation prevention groove, and a coil securedto a periphery of the lower bobbin portion; at least one magnet facingthe coil; a yoke fixing the at least one magnet and comprising arotation prevention unit extended to the rotation prevention groove toface the upper bobbin portion; and an elastic member supporting thebobbin, wherein the rotation prevention unit comprises: a lateralportion extending laterally from the yoke; and a downward portionextending downwardly into the rotation prevention groove and toward theupper surface of the lower bobbin portion.
 18. The voice coil motor ofclaim 17, wherein the yoke further comprises: an upper plate having anopening for exposing the bobbin, and a lateral plate connected to theupper plate and fixing the magnet, wherein the lateral portion of therotation prevention unit is extended from part of the upper plate of theyoke, and wherein the downward portion of the rotation prevention unitis disposed in the rotation prevention groove of the upper bobbinportion.
 19. The voice coil motor of claim 17, wherein a thickness ofthe upper bobbin portion is thinner than that of the lower bobbinportion.
 20. The voice coil motor of claim 17, wherein the lateralportion of the rotation prevention unit and the downward portion of therotation prevention unit are integrally formed with the yoke.
 21. Thevoice coil motor of claim 17, wherein the yoke further comprises aplurality of rotation prevention units, the upper bobbin portioncomprises a plurality of rotation prevention grooves, and the downwardportion of each rotation prevention unit is disposed in a rotationprevention groove of the plurality of rotation prevention grooves.